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Title:Coolant and Antifreeze

Describing the Principle: Water has a freezing point of 32 degrees Fahrenheit. It also has a boiling point of 212 degrees Fahrenheit. However, the coolant in a typical engine needs to be able to operate in colder temperatures as well as higher temperatures in the engine. This is the reason antifreeze is added to the coolant. Antifreeze does two things to the coolant. It causes its freezing point to go down and its boiling point to go up. Looking at the illustration to the left, this chart shows what happens to the freezing point as the percentage of antifreeze is increased. For example, a mixture of 50% antifreeze and 50% water has a freezing point of – 34 degrees Fahrenheit. At 68% antifreeze, the freezing point of the coolant is now as low as it can go or about -92 degrees Fahrenheit. If the percentage of antifreeze increases beyond this point the freezing point goes back up to about – 6 degrees Fahrenheit at 100 % antifreeze.This information helps to build a better street rod, custom hot rod, or vintage car.

As antifreeze is added to the coolant, the boiling point also increases. Referring to the illustration on the left, note that at 50% antifreeze and 50% water, the boiling point is now increased to 226 degrees Fahrenheit. At 70% antifreeze and 30% water, the boiling point goes up to 238 degrees Fahrenheit. Knowing these two principles, the best water to antifreeze ratio is about 68% antifreeze and 32% water. Under these conditions, the ideal freezing and high temperature protection will be achieved in the cooling system. Back to Mechanical Principles